EE have confirmed that my iphone is unlocked but it will not accept 3 UK sim, when connected to iTunes it states Locked to carrier sim card not supported

Hi I have an iPhone 5C from a work colleague that was on the EE network, A request was made to EE Customer services for the phone to be unlocked, they sent a confirmation text on Xmas eve confirming this had been completed. The phone will not accept any other service providers sim and when connected to iTunes comes up with the sim not supported message, EE did state that it may take up to 10 days to put the unlock through but ( due to festive holidays) but then sent a confirmation txt the next day. I understand that EE makes the unlock request to apple so am I waiting on apple or are EE just being a bit previous with their confirmation txt.

Any one else had any experience on actual unlocking time scales?